At the entrance, visitors are greeted by a majestic oak — more precisely a quercus robur with a massive trunk and rugged bark — which gives way to a dense grove of bamboo. Located outside the circular wall of the garden, the Arboretum dates back to the second half of the 18th century and offers an evocative journey among those great keepers of the garden, the historic trees paraded in all their ancient majesty: the gigantic oriental plane tree of 1680 with its hollow trunk, in all probability struck by lightning, and a short distance away, trying in vain not to arouse suspicion, a group of banana plants do their utmost to pose as trees, whereas in reality they are uncommonly large herbaceous plants. One avenue bears the name of the plants it features — palms — symbolic of grace and elegance, and near the west gate of the Renaissance Garden, as well as in other areas, is the tulip tree, with its leaves that recall the head of a cat, and large flowers that blossom in springtime amongst the fronds, resembling the tulip as its name suggests. Rising between the south and west gates are the high tops of the beech, the narrow-leaved ash, the Caucasian elm and the horse chestnut, in effect an oak with serrated leaves. Also represented are the swamp oak and the pecan, a tree cultivated for its nutrient-rich seeds. A few steps toward the east gate are the Himalayan Cedar (the first specimen of this species to have been introduced into Italy, in 1828), the Atlas cedar and the cedar of Lebanon.